Micro Focus Expert
Micro Focus Expert

(DP) Support Tip: Restrictions for Cell Manager Hostnames

There are several restrictions regarding the DP Cell Manager hostname and the domain name components.
If these restrictions are not minded, there will be issues with the certificate creation and the DP Application Server. These restrictions are valid for DP 9 and 10. For DP 9, issues have only been visible wihen using the advanced scheduler. For DP 10, these issues will affect a wider range of the product.

Not all of these restrictions are intercepted during the installation, they need to be checked manually before installing the product or updating it.


The first character of a hostname or domain component must be letter.
A hostname or domain components must not consist of a single character.

Certificate generation is done by the Oracle Java Security Tools (which we use inside DP). The Oracle Java Security Tools insists on strict follow of RFC 952 standard when checking for host names and domain components. The RFC 952 insists that the first character of hostname and every domain component must be letter and that the domain components do not consist of a single character. This is changed in RFC 1123. There is already a request to relax the hostname handling in Oracle Java Tools to comply with the RFC 1123, but it is not resolved yet: http://bugs.java.com/bugdatabase/view_bug.do?bug_id=8054380



Hostnames may not contain other special characters than a minus sign (-)

As described in RFC-0952, host names may only consist of: A "name" (Net, Host, Gateway, or Domain name) is a text string up to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus sign (-), and period (.). Note that periods are only allowed when they serve to delimit components of "domain style names".https://www.rfc-editor.org/rfc/rfc952.txt



Hostname longer than 15 characters:

Windows does not permit computer names that exceed 15 characters.
Source: https://support.microsoft.com/en-us/help/909264/naming-conventions-in-active-directory-for-computers-domains-sites-and



In case you encounter one of these hostnames for your DP Cell Manager, consult support.
Do not install the product or update it!

1 Reply
Roland Wilder Regular Contributor.
Regular Contributor.

Re: (DP) Support Tip: Restrictions for Cell Manager Hostnames

I guess they ought to get a jump on this as the new standard has been out for some time.

RFC 1123 for host naming.

2.1 Host Names and Numbers

The syntax of a legal Internet host name was specified in RFC-952
[DNS:4]. One aspect of host name syntax is hereby changed: the
restriction on the first character is relaxed to allow either a
letter or a digit. Host software MUST support this more liberal

Host software MUST handle host names of up to 63 characters and
SHOULD handle host names of up to 255 characters.

Whenever a user inputs the identity of an Internet host, it SHOULD
be possible to enter either (1) a host domain name or (2) an IP
address in dotted-decimal ("#.#.#.#") form. The host SHOULD check
the string syntactically for a dotted-decimal number before
looking it up in the Domain Name System.

This last requirement is not intended to specify the complete
syntactic form for entering a dotted-decimal host number;
that is considered to be a user-interface issue. For
example, a dotted-decimal number must be enclosed within
"[ ]" brackets for SMTP mail (see Section 5.2.17). This
notation could be made universal within a host system,
simplifying the syntactic checking for a dotted-decimal

If a dotted-decimal number can be entered without such
identifying delimiters, then a full syntactic check must be
made, because a segment of a host domain name is now allowed
to begin with a digit and could legally be entirely numeric
(see Section However, a valid host name can never
have the dotted-decimal form #.#.#.#, since at least the
highest-level component label will be alphabetic.

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